The present invention relates to a desiccant absorption power plant using the combination of an open air evaporator and a demineralizer to purify required boiler feedwater.
Kasley (1935), U.S. Pat. No. 2,005,377, describes an absorption power plant using an inexpensive open air evaporator and using tapwater as boiler feedwater. However, his plant preheats water and desiccant brine streams to high temperatures and directly boils water to steam creating serious corrosion and mineral deposit problems which outweight the advantage of the open evaporator. To avoid this corrosion and deposits problem, Isshiki et al., U.S. Pat. No. 4,122,680, describes a low temperature (vacuum) process and Natanson (1885) U.S. Pat. No. 327,300 describes an indirect, flash-boiling process, but neither use the evaporative capacity of air to drive water from liquid desiccant brine in an open cycle and thereby suffer low cycle efficiency and high cost. Features of the present invention described herein make the inexpensive, open evaporator feasible.
The present invention reduces potential for deposits of minerals in the boiler by at least partially demineralizing the feedwater stream (as of calcium and magnesium salts, for example) prior to introduction to the boiler.